Portable tools



D 3, 1968 D. N. w. BADCOCK 3,414,748

PORTABLE TOOLS Original Filed April 17, 1964 3 Sheets-Sheet 1 no 194 m Dec. 3, 1968 D. N. w. BADCOCK PORTABLE TOOLS 3 Sheets-Sheet 2 Original Filed April 1'7, 1964 Dn m) 41mm an 1/; m0 Bobcat Dec. 3, 1968 D. N. w. BADCOCK PORTABLE TOOLS 5 Sheets-Sheet 5 Original Filed April 17, 1964 Jar/D Mam/w uJ/LA/ 3024M m aw/'02 $41/y/QMJ United States Patent 3,414,748 PORTABLE TOOLS David Norman William Badcock, London, England, as-

signor to Kango Electric Hammers Limited, London, England Original application Apr. 17, 1964, Ser. No. 360,630. Divided and this application May 17, 1967, Ser. No. 641,741 Claims priority, application Great Britain, Apr. 22, 1963, 15,820/ 63 3 Claims. (Cl. 310-50) ABSTRACT OF THE DISCLOSURE A portable electrically driven power tool comprising a housing portion, an electric motor mounted in the housing portion, a hand grip, supporting strut means extending between the housing portion and the hand grip, a switch for the motor which switch is mounted in the housing portion, an operating lever for the switch which lever is mounted wholly on the hand grip, a separate motion transmitting device operatively interconnecting the operating lever and the switch, and a cable entry assembly accommodated within the housing portion, the hand grip and the switch being disposed one on each side of and coplanar with the cable entry assembly, and the motion transmitting device comprising twin switch actuating elements extending past opposite sides of the cable entry assembly.

This is a division of application Ser. No. 360,630, filed Apr. 17, 1964, now abandoned.

This invention relates to portable electrically driven power tools and has for its object to provide tools of this kind which are safer than heretofore.

Several existing portable electric hammers and other such tools have employed a handle with a grip portion incorporating a rockable switch operating lever, and customarily flexible electrical conductors have been brought into the handle for connection with a switch mounted in the hand grip, the power supply cables passing directly into the tool motor housing on which the handle has been directly mounted. Tools of this kind are very convenient for operating purposes but are often mishandled and subjected even to violent abuse so that it is not uncommon for a handle to be smashed by a blow or wrenched off, thereby exposing live connections; moreover, where protective insulation is damaged the bared conductors may render live metallic parts of the enclosure of the tool.

According to the present invention there is provided a portable electrically driven power tool comprising a housing portion, an electric motor mounted in the housing portion, a hand grip, supporting strut means extending between the housing portion, and the hand grip, a switch for the motor, and an operating lever for the switch which lever is mounted wholly on the hand grip characterised in that the switch is mounted in the housing portion and in that a separate motion transmitting device is provided operatively interconnecting the operating lever and the switch. Preferably the hand grip and the supporting strut means are formed integrally with a member which constitutes a closure of the housing portion.

In preferred constructions a cable entry assembly is accommodated within the housing portion, the hand grip and the switch being disposed one on each side of and coplanar with the cable entry assembly, and the motion transmitting device comprising twin switch actuating elements extending past opposite sides of the cable entry assembly. Preferably the actuating elements comprise parallel rods made from an electrically insulating material and yoked together.

3,414,748 Patented Dec. 3, 1968 One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a fragmentary perspective view showing the switch gear applied to a double-insulated electric motor for a portable percussive tool; the motor housing is shown in chain-dot lines,

FIGURE 2 is a part-sectional elevation through the motor housing and tool handle, and

FIGURE 3 is a partial longitudinal section taken at right angles to the section in FIGURE 2, that is, along line IIIIII of FIGURE 2.

The handle assembly of the portable tool comprises a base 101 which forms an end closure for a motor housing par-t 102, a spigot 103 being provided on said base 101 for location within the open end of the motor housing part 102.

The hand grip 104 comprises a tube connected to the base 101 by a pair of struts formed by a solid web 106 at one end and by a hollow webbed pillar 107 at the other end; a part of said grip tube 104 may be partially or completely enclosed in a sheath (not shown) of moderately resilient rubber or the like.

Within the grip tube 104 is accommodated the major part of an operating lever 109 rockable on any intermediate cross-pin 110, the longer portion of lever 109 having a head 111 adapted to project through a longitudinal slot 112 in the grip tube 104. The tail 113 of lever 109 carries an adjustable screw stop 114 adapted to apply pressure, through a leaf element hinged on an integral projection 108, to one end of a plunger 115 slidable within the bore of pillar 107, and thus compensate for manufacturing variations in the various components concerned with switch operation.

It is preferred to employ centrally located means for the entry of the trailing power cable, that is, in the same plane as grip tube 104. Accordingly the cable entry assembly 16 lies athwart the plunger 115 and prevents in-line mechanical connection with a switch 117 contained in the switch chamber 129 of the motor housing 102.

The cable entry assembly 116 comprises a cable end housing 118 made of a suitable insulating material and having a tubular spigot 119 receivable within a hole 120 in motor housing part 102, a resilient sheath 121 as customarily employed on the end of a trailing power cable being receivable within the bore of housing 118. The cable end housing 118 is provided with flanges 122 whereby the housing 118 may be secured, by screws 123, to motor housing part 102.

For securing cable sheath 121 in position a locking bridge 124, also made of insulating material, is adapted to be secured, by screws (not shown) to housing 118 so that a block 126 on said bridge enters a through slot 127 in the housing 118 to bear against sheath 121. The end of the power cable (not shown) is passed through an angled protective duct 128 of insulating material to enable the cable ends to be connected to switch 117.

There is no need for flexible conductor wires to extend between the handle grip tube 104 and the switch chamber 129 in motor housing part 102, since use is made of a motion transmitting device 130 comprising a pair of rods 131 made of insulating material and yoked together at opposite ends by tie bars 132 and 132A, said rods 131 passing through parallel holes 133 in motor housing part 102, at opposite sides of the hole 120 which receives the cable end housing spigot 119.

The tie bar 132 is adapted to be pressed upon by plunger 115 as it is projected under direct action of operating lever 109 in hand grip 104, thereby to displace rods 131 and, through tie bar 132A and a strut 134, to move the operatin member or tumbler 135 to operate switch 117 against the restraint of the return springs 135a of member 135 which springs operate to return member 135, rods 131, plunger 115 and lever 109 to their rest positions. The switch 117 may be of such a construction that it would remain on if pressure on lever 109 is relieved, another gripping action on said lever being required to project plunger 115 forward again to switch off switch 117.

For double-insulating purposes, the switch chamber 129 has a moulded box-like liner 137 of insulating material, suitably apertured for the passage of various components which project into said liner. The switch chamber 129 is made without a roof, so that the flat top 138 of liner 137 is exposed in the interior of motor housing and lies in close proximity to the stator assembly 142, whilst outward projection of the switch chamber is reduced to a minimum.

The liner 137 is held in switch chamber 129 in any suitable manner, such as by pressure applied through rubber blocks by abutment strips 136 in a switch chamber cover 139, or by a liner in said cover; the liner 137 has integral side blocks 140, to which switch 117 may be secured by the screws 125 which force it onto the resilient mountings 141.

The drawings show the switch disposed in a chamber adjacent the motor armature commutator 143 onto which are pressed brushes 144 carried by a mounting ring 145. Coaxial With the brush mounting ring 145 is a pressure ring 146 which abuts one end of the stator assembly 142, and a set of wavy Washers 147 is interposed between the rings 145 and 146 to provide resilient axial loading, the other end of stator assembly 142 seating within an insulating sleeve 148 which encloses said stator assembly and lines the motor housing 102; this axial loading of the coaxial sleeve 148, pressure ring 146 and brush mounting ring 145 is more fully described in my copending application Ser. No. 360,630. A ventilating fan 149 is carried by the armature 150, which through gearing 151 operates mechanism within the tool housing 152.

I claim:

1. A portable electrically driven power tool comprising a housing portion, an electric motor mounted in the housing portion, a hand grip, supporting strut means extending between the housing portion and the hand grip, a switch for the motor which switch is mounted in the housing portion, an operating lever for the switch which lever is mounted wholly on the hand grip, a separate motion transmitting device operatively interconnecting the operating lever and the switch, and a cable entry assembly accommodated within the housing portion, and the hand grip and the switch being disposed one on each side of and coplanar with the cable entry assembly, and the motion transmitting device comprisin twin switch actuating elements extending past opposite sides of the cable entry assembly.

2. A portable tool as claimed in claim 1 in which the actuating elements comprise parallel rods made from an electrically insulating material and yoked together.

3. A portable tool as claimed in claim 2, further comprising tie bars yoking the rods together at their ends, and a plunger slidably mounted in the strut means and extending between the operating lever and one of the tie bars.

References Cited UNITED STATES PATENTS MILTON O. HIRSHFIELD, Primary Examiner. G. NUNEZ, Assistant Examiner. 

